fix: keep accepting an adapter without watch

The new configuration check required `watch`, but four runtime roles ask
`respond_to?(:watch)` before they use it, and ADR 0011 records that an
older adapter without it keeps the fast polling cadence. A supported
adapter would have failed at boot. The check requires `signal` and
`wait`, which every role calls without asking.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: cardmagic

lib/solid_objects/configuration.rb

@@ -266,7 +266,7 @@ def validate_wake_up_adapter!
 
     # @rbs () -> void
     def validate_wake_up_object!
-      %i[signal wait watch].each do |method_name|
+      %i[signal wait].each do |method_name|
         next if wake_up_adapter.respond_to?(method_name)
 
         raise ArgumentError, "wake_up_adapter must respond to #{method_name}"

test/integration/wake_up_selection_test.rb

@@ -131,6 +131,25 @@ def wait(timeout:) = false
       warnings.map { |payload| payload[:event].to_s }
   end
 
+  test "an adapter without watch is still accepted" do
+    legacy = Class.new do
+      def signal = true
+
+      def wait(timeout:) = false
+    end.new
+    SolidObjects.configuration.wake_up_adapter = legacy
+
+    assert_same SolidObjects.configuration, SolidObjects.configuration.validate!
+    assert_same legacy, SolidObjects.wake_up
+  end
+
+  test "an adapter that cannot signal is refused" do
+    SolidObjects.configuration.wake_up_adapter = Object.new
+
+    error = assert_raises(ArgumentError) { SolidObjects.configuration.validate! }
+    assert_match(/signal/, error.message)
+  end
+
   test "an unknown name is refused when the configuration is validated" do
     SolidObjects.configuration.wake_up_adapter = :carrier_pigeon